/*      $NetBSD: mdreloc.c,v 1.11 2024/12/01 09:27:12 skrll Exp $       */

/*-
 * Copyright (c) 2014 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Thomas of 3am Software Foundry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: mdreloc.c,v 1.11 2024/12/01 09:27:12 skrll Exp $");
#endif /* not lint */

/*
 * RISC-V ELF relocations.
 *
 * Reference:
 *
 *      [RISCVELF] RISC-V ELF Specification, 2024-07-17.
 *      https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/9fec6080d15e7f009c9e714d1e9b8dd7177b0b67/riscv-elf.adoc
 */

#include <sys/types.h>
#include <sys/endian.h>
#include <sys/tls.h>

#include <machine/lwp_private.h>

#include <stdlib.h>
#include <string.h>

#include "debug.h"
#include "rtld.h"

void _rtld_bind_start(void);
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
void *_rtld_bind(const Obj_Entry *, Elf_Word);

void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
        obj->pltgot[0] = (Elf_Addr) &_rtld_bind_start;
        obj->pltgot[1] = (Elf_Addr) obj;
}

void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
        const Elf_Rela *rela = NULL, *relalim;
        Elf_Addr relasz = 0;

        for (; dynp->d_tag != DT_NULL; dynp++) {
                switch (dynp->d_tag) {
                case DT_RELA:
                        rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
                        break;
                case DT_RELASZ:
                        relasz = dynp->d_un.d_val;
                        break;
                }
        }

        relalim = (const Elf_Rela *)((uintptr_t)rela + relasz);
        for (; rela < relalim; rela++) {
                Elf_Word r_type = ELF_R_TYPE(rela->r_info);
                Elf_Addr *where = (Elf_Addr *)(relocbase + rela->r_offset);

                switch (r_type) {
                case R_TYPE(RELATIVE): {
                        Elf_Addr val = relocbase + rela->r_addend;
                        *where = val;
                        rdbg(("RELATIVE/L(%p) -> %p in <self>",
                            where, (void *)val));
                        break;
                    }

                case R_TYPE(NONE):
                        break;

                default:
                        abort();
                }
        }
}

int
_rtld_relocate_nonplt_objects(Obj_Entry *obj)
{
        const Elf_Rela *rela;
        const Elf_Sym *def = NULL;
        const Obj_Entry *defobj = NULL;
        unsigned long last_symnum = ULONG_MAX;

        for (rela = obj->rela; rela < obj->relalim; rela++) {
                Elf_Addr * const where =
                    (Elf_Addr *)(obj->relocbase + rela->r_offset);
                const Elf_Word r_type = ELF_R_TYPE(rela->r_info);
                unsigned long symnum;

                switch (r_type) {
                case R_TYPESZ(ADDR):
                case R_TYPESZ(TLS_DTPMOD):
                case R_TYPESZ(TLS_DTPREL):
                case R_TYPESZ(TLS_TPREL):
                        symnum = ELF_R_SYM(rela->r_info);
                        if (last_symnum != symnum) {
                                last_symnum = symnum;
                                def = _rtld_find_symdef(symnum, obj, &defobj,
                                    false);
                                if (def == NULL)
                                        return -1;
                        }
                        break;
                default:
                        break;
                }

                switch (r_type) {
                case R_TYPE(NONE):
                        break;

                case R_TYPE(RELATIVE): {
                        const Elf_Addr val = (Elf_Addr)obj->relocbase +
                            rela->r_addend;

                        rdbg(("RELATIVE(%p) -> %p (%s) in %s",
                            where, (void *)val,
                            obj->strtab +
                                obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
                            obj->path));

                        *where = val;
                        break;
                    }

                case R_TYPESZ(ADDR): {
                        const Elf_Addr val = (Elf_Addr)defobj->relocbase +
                            def->st_value + rela->r_addend;

                        rdbg(("ADDR(%p) -> %p (%s) in %s%s",
                            where, (void *)val,
                            obj->strtab +
                                obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
                            obj->path,
                            def == &_rtld_sym_zero ? " (symzero)" : ""));

                        *where = val;
                        break;
                    }

                case R_TYPE(COPY):
                        /*
                         * These are deferred until all other relocations have
                         * been done.  All we do here is make sure that the
                         * COPY relocation is not in a shared library.  They
                         * are allowed only in executable files.
                         */
                        if (obj->isdynamic) {
                                _rtld_error("%s: Unexpected R_COPY relocation"
                                    " in shared library", obj->path);
                                return -1;
                        }
                        rdbg(("COPY (avoid in main)"));
                        break;

                case R_TYPESZ(TLS_DTPMOD): {
                        const Elf_Addr val = (Elf_Addr)defobj->tlsindex;

                        rdbg(("TLS_DTPMOD(%p) -> %p (%s) in %s",
                            where, (void *)val,
                            obj->strtab +
                                obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
                            obj->path));

                        *where = val;
                        break;
                    }

                case R_TYPESZ(TLS_DTPREL): {
                        const Elf_Addr val = (Elf_Addr)(def->st_value +
                            rela->r_addend - TLS_DTV_OFFSET);

                        rdbg(("TLS_DTPREL(%p) -> %p (%s) in %s",
                            where, (void *)val,
                            obj->strtab +
                                obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
                            defobj->path));

                        *where = val;
                        break;
                    }

                case R_TYPESZ(TLS_TPREL):
                        if (!defobj->tls_static &&
                            _rtld_tls_offset_allocate(__UNCONST(defobj)))
                                return -1;

                        *where = (Elf_Addr)(def->st_value + defobj->tlsoffset +
                            rela->r_addend);

                        rdbg(("TLS_TPREL %s in %s --> %p in %s",
                            obj->strtab +
                                obj->symtab[ELF_R_SYM(rela->r_info)].st_name,
                            obj->path, (void *)*where, defobj->path));
                        break;

                default:
                        rdbg(("sym = %lu, type = %lu, offset = %p, "
                            "addend = %p, contents = %p",
                            (u_long)ELF_R_SYM(rela->r_info),
                            (u_long)ELF_R_TYPE(rela->r_info),
                            (void *)rela->r_offset, (void *)rela->r_addend,
                            (void *)*where));
                        _rtld_error("%s: Unsupported relocation type %ld "
                            "in non-PLT relocations",
                            obj->path, (u_long)r_type);
                        return -1;
                }
        }

        return 0;
}

int
_rtld_relocate_plt_lazy(Obj_Entry *obj)
{

        if (!obj->relocbase)
                return 0;

        for (const Elf_Rela *rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
                Elf_Addr *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
                switch (ELF_R_TYPE(rela->r_info)) {
                case R_TYPE(JMP_SLOT):
                        /* Just relocate the GOT slots pointing into the PLT */
                        *where += (Elf_Addr)obj->relocbase;
                        rdbg(("fixup !main in %s --> %p", obj->path, (void *)*where));
                        break;
                default:
                        rdbg(("not yet... %d", (int)ELF_R_TYPE(rela->r_info) ));
                }
        }

        return 0;
}

static int
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela,
    Elf_Addr *tp)
{
        Elf_Addr * const where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
        const Obj_Entry *defobj;
        Elf_Addr new_value;

        assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));

        const Elf_Sym *def = _rtld_find_plt_symdef(ELF_R_SYM(rela->r_info),
            obj, &defobj, tp != NULL);
        if (__predict_false(def == NULL))
                return -1;
        if (__predict_false(def == &_rtld_sym_zero))
                return -1;

        if (ELF_ST_TYPE(def->st_info) == STT_GNU_IFUNC) {
                if (tp == NULL)
                        return 0;
                new_value = _rtld_resolve_ifunc(defobj, def);
        } else {
                new_value = (Elf_Addr)(defobj->relocbase + def->st_value);
        }
        rdbg(("bind now/fixup in %s --> old=%p new=%p",
            defobj->strtab + def->st_name, (void *)*where,
            (void *)new_value));
        if (*where != new_value)
                *where = new_value;
        if (tp)
                *tp = new_value;

        return 0;
}

void *
_rtld_bind(const Obj_Entry *obj, Elf_Word gotoff)
{
        const Elf_Addr relidx = (gotoff / sizeof(Elf_Addr));
        const Elf_Rela *pltrela = obj->pltrela + relidx;

        Elf_Addr new_value = 0;

        _rtld_shared_enter();
        const int err = _rtld_relocate_plt_object(obj, pltrela, &new_value);
        if (err)
                _rtld_die();
        _rtld_shared_exit();

        return (void *)new_value;
}

int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{

        for (const Elf_Rela *rela = obj->pltrela; rela < obj->pltrelalim; rela++) {
                if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
                        return -1;
        }

        return 0;
}